Injection systems are used to inject fuel into combustion chambers of an internal combustion engine, in particular a diesel internal combustion engine, which injection systems have been increasingly configured in the last years as what are known as “common rail” systems. In the latter, the injectors which are arranged in the combustion chambers are supplied with fuel from a common fuel accumulator, the common rail. Here, the fuel which is to be injected is present in the fuel accumulator at a pressure of up to over 2000 bar.
Injection systems for internal combustion engines usually have various pumps, by means of which fuel is conveyed, in order to be introduced into combustion chambers of the internal combustion engine. Injection systems of this type for internal combustion engines make high requirements of the accuracy of the injection pressure which is required for the injection of the fuel into the combustion chambers of the internal combustion engine.
This is particularly important, since more and more stringent legal regulations are being passed with regard to the permissible pollutant emissions of internal combustion engines which are arranged in motor vehicles. Said legal regulations make it necessary to take various measures, by which the pollutant emissions are reduced. Thus, for example, the formation of soot is greatly dependent on the preparation of the air/fuel mixture in the respective cylinder of the internal combustion engine. Here, it is advantageous for the reduction in the pollutant emissions if the fuel can be injected very precisely into the cylinder.
EP 1 296 060 B1 has disclosed an injection system for an internal combustion engine, having a prefeed pump, by way of which fuel can be conveyed out of a fuel tank to the suction side of a high pressure pump. A high pressure pump which is connected hydraulically behind the prefeed pump then conveys fuel into a fuel accumulator, from where it can then be distributed to injectors which are coupled hydraulically to the fuel accumulator. In the case of a suitable actuation of the high pressure pump, a predefined pressure which is dependent on the operating parameters of the internal combustion engine can be reached in the fuel accumulator.